Effects of hard fats on in vitro and in vivo rumen fermentation, milk production and reproduction in dairy cows.
Adding 0, 5, 15, and 20% of substrate as prilled or unprilled fatty acids [palmitic (47 to 48%), stearic (36 to 37%), and oleic (14%) acids] to an in vitro rumen fermenter had no effect on total VFA production. Acetate:propionate ratio was reduced by fatty acid concentrations of 15 and 20% (prilled and unprilled). In a 4 x 4 Latin square, increasing dietary prilled fatty acids (0, 3, 6, or 9% of DM) decreased DM intake, increased percentage of milk fat, and had no effect on percentage of milk protein. Milk volume and FCM increased with 3% but decreased with 6 and 9% dietary fatty acids. Rumen fluid acetate:propionate decreased with increasing dietary fatty acids. Holstein cows in three herds in Pennsylvania and Friesian cows in an Israeli herd were assigned randomly to receive, from 0 to 110 to 150 d postcalving, diets containing 0 or 2% of DM prilled fat. In Israel, dietary fat increased milk yield, FCM, and fat percentage during the first 90 d postcalving. In Pennsylvania, prilled fat had variable effects on milk composition and little effect on milk yield and FCM. Conception rate was improved in cows consuming rations containing prilled fat: first service, 59.1 versus 42.6%; all services, 59.3 versus 40.7%. The inclusion of prilled fat at 2% of DM in dairy cattle rations had slight effects on rumen fermentation, variable effects on milk yield and composition, and beneficial effects on conception rate.
Ferguson
J D
JD
Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine, Kennett Square 19382.
Sklan
D
D
Chalupa
W V
WV
Kronfeld
D S
DS
D000818:Animals; D002417:Cattle / Q000502:physiology*; D004041:Dietary Fats / Q000494:pharmacology*; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005260:Female; D005285:Fermentation; D005306:Fertilization; D066298:In Vitro Techniques; D007774:Lactation; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000032:analysis; D011247:Pregnancy; D011897:Random Allocation; D012417:Rumen / Q000378:metabolism*
D004041:Dietary Fats; D005232:Fatty Acids, Volatile; D008894:Milk Proteins